1. Field of the Invention
The present invention relates to a synchronous serial transfer apparatus and a synchronous serial transfer method, and more particularly, to an apparatus for and a method of performing a synchronous serial transfer which reduces the number of communication lines which connect a plurality of communication apparatuses to each other.
2. Description of the Background Art
FIG. 35 shows a structure of a conventional synchronous serial transfer apparatus for performing a synchronous serial transfer. In FIG. 35, n communication apparatuses SL1 to SLn are connected to a communication apparatus SLM. The communication apparatus SLM and the communication apparatuses SL1 to SLn are electrically connected to each other by wire line groups LG which include data transmission lines 38, data receive lines 39, clock lines 40 for synchronizing a transfer between a transmit end and a receiving end and control signal lines 41.
That is, the plurality of wire line groups LG extend from the communication apparatus SLM and are respectively connected to the communication apparatuses SL1 to SLn. With the communication apparatus SLM serving as a master apparatus and the communication apparatuses SL1 to SLn serving as slave apparatuses, communication is performed only between the master apparatus and the slave apparatuses. Communication between the slave apparatuses are performed through the master apparatus.
Having such a structure as described above, the conventional synchronous serial transfer apparatus requires the wire line groups each containing four lines to electrically connect the master apparatus and the slave apparatuses. As the number of the slave apparatuses increases, more lines are necessary, thereby making control over a serial transfer complex. In addition, since it is necessary that the master apparatuses contains in advance a structure for connecting a number of the slave apparatuses, the master apparatus is large.